from array import array
from struct import pack, unpack

_SM4_FK = array('L', [0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc])
_SM4_CK = array('L', [
    0x00070e15, 0x1c232a31, 0x383f464d, 0x545b6269, 0x70777e85, 0x8c939aa1, 0xa8afb6bd, 0xc4cbd2d9,
    0xe0e7eef5, 0xfc030a11, 0x181f262d, 0x343b4249, 0x50575e65, 0x6c737a81, 0x888f969d, 0xa4abb2b9,
    0xc0c7ced5, 0xdce3eaf1, 0xf8ff060d, 0x141b2229, 0x30373e45, 0x4c535a61, 0x686f767d, 0x848b9299,
    0xa0a7aeb5, 0xbcc3cad1, 0xd8dfe6ed, 0xf4fb0209, 0x10171e25, 0x2c333a41, 0x484f565d, 0x646b7279])
_SM4_S_BOX = bytes([
    0xd6, 0x90, 0xe9, 0xfe, 0xcc, 0xe1, 0x3d, 0xb7, 0x16, 0xb6, 0x14, 0xc2, 0x28, 0xfb, 0x2c, 0x05,
    0x2b, 0x67, 0x9a, 0x76, 0x2a, 0xbe, 0x04, 0xc3, 0xaa, 0x44, 0x13, 0x26, 0x49, 0x86, 0x06, 0x99,
    0x9c, 0x42, 0x50, 0xf4, 0x91, 0xef, 0x98, 0x7a, 0x33, 0x54, 0x0b, 0x43, 0xed, 0xcf, 0xac, 0x62,
    0xe4, 0xb3, 0x1c, 0xa9, 0xc9, 0x08, 0xe8, 0x95, 0x80, 0xdf, 0x94, 0xfa, 0x75, 0x8f, 0x3f, 0xa6,
    0x47, 0x07, 0xa7, 0xfc, 0xf3, 0x73, 0x17, 0xba, 0x83, 0x59, 0x3c, 0x19, 0xe6, 0x85, 0x4f, 0xa8,
    0x68, 0x6b, 0x81, 0xb2, 0x71, 0x64, 0xda, 0x8b, 0xf8, 0xeb, 0x0f, 0x4b, 0x70, 0x56, 0x9d, 0x35,
    0x1e, 0x24, 0x0e, 0x5e, 0x63, 0x58, 0xd1, 0xa2, 0x25, 0x22, 0x7c, 0x3b, 0x01, 0x21, 0x78, 0x87,
    0xd4, 0x00, 0x46, 0x57, 0x9f, 0xd3, 0x27, 0x52, 0x4c, 0x36, 0x02, 0xe7, 0xa0, 0xc4, 0xc8, 0x9e,
    0xea, 0xbf, 0x8a, 0xd2, 0x40, 0xc7, 0x38, 0xb5, 0xa3, 0xf7, 0xf2, 0xce, 0xf9, 0x61, 0x15, 0xa1,
    0xe0, 0xae, 0x5d, 0xa4, 0x9b, 0x34, 0x1a, 0x55, 0xad, 0x93, 0x32, 0x30, 0xf5, 0x8c, 0xb1, 0xe3,
    0x1d, 0xf6, 0xe2, 0x2e, 0x82, 0x66, 0xca, 0x60, 0xc0, 0x29, 0x23, 0xab, 0x0d, 0x53, 0x4e, 0x6f,
    0xd5, 0xdb, 0x37, 0x45, 0xde, 0xfd, 0x8e, 0x2f, 0x03, 0xff, 0x6a, 0x72, 0x6d, 0x6c, 0x5b, 0x51,
    0x8d, 0x1b, 0xaf, 0x92, 0xbb, 0xdd, 0xbc, 0x7f, 0x11, 0xd9, 0x5c, 0x41, 0x1f, 0x10, 0x5a, 0xd8,
    0x0a, 0xc1, 0x31, 0x88, 0xa5, 0xcd, 0x7b, 0xbd, 0x2d, 0x74, 0xd0, 0x12, 0xb8, 0xe5, 0xb4, 0xb0,
    0x89, 0x69, 0x97, 0x4a, 0x0c, 0x96, 0x77, 0x7e, 0x65, 0xb9, 0xf1, 0x09, 0xc5, 0x6e, 0xc6, 0x84,
    0x18, 0xf0, 0x7d, 0xec, 0x3a, 0xdc, 0x4d, 0x20, 0x79, 0xee, 0x5f, 0x3e, 0xd7, 0xcb, 0x39, 0x48])
_SM4_S_BOX_FAST = array('H')
for byte1 in _SM4_S_BOX:  # 构造两字节的S盒变换表
    byte1 <<= 8
    _SM4_S_BOX_FAST.extend(byte1 | byte2 for byte2 in _SM4_S_BOX)


def _T_key(ka):  # 用于生成圈密钥的T'变换
    B = _SM4_S_BOX_FAST[ka >> 16] << 16 | _SM4_S_BOX_FAST[ka & 0xffff]  # S盒变换
    return (B ^ (B << 13 | B >> 19) ^ (B << 23 | B >> 9)) & 0xffffffff  # L线性变换


def _T(x):  # T变换
    B = _SM4_S_BOX_FAST[x >> 16] << 16 | _SM4_S_BOX_FAST[x & 0xffff]  # S盒变换
    return (B ^ (B << 2 | B >> 30) ^ (B << 10 | B >> 22) ^ (B << 18 | B >> 14)
            ^ (B << 24 | B >> 8)) & 0xffffffff  # L线性变换


def _one_round(rK, X):  # T变换
    X0, X1, X2, X3 = X
    for rk in rK:
        X0, X1, X2, X3 = X1, X2, X3, X0 ^ _T(X1 ^ X2 ^ X3 ^ rk)
    return [X3, X2, X1, X0]


def _ecb_base(rK, X):
    for i in range(0, len(X), 4):  # 4个字为一组
        X[i:i + 4] = _one_round(rK, X[i:i + 4])
    return X


def _cbc_enc(rK, iv, X):
    for i in range(0, len(X), 4):
        iv = X[i:i + 4] = _one_round(rK, [X[i + j] ^ iv[j] for j in range(4)])
    return X


def _cbc_dec(rK, iv, X):
    for i in range(0, len(X), 4):
        next_iv = X[i:i + 4]
        X[i:i + 4], iv = list(map(lambda x, y: x ^ y, _one_round(rK, X[i:i + 4]), iv)), next_iv
    return X


# bytes转数组（4个字节为一字）
def byte2array(data):
    return list(unpack('>%dI' % (len(data) >> 2), data))


# 数组转bytes
def array2byte(data):
    return pack('>%dI' % (len(data)), *data)


class SM4:
    def __init__(self, key):
        self.set_key(key)

    def set_key(self, key):
        MK = unpack('>4I', key)
        K = array('L', (MK[i] ^ _SM4_FK[i] for i in range(4)))
        K.extend(K[i] ^ _T_key(K[i + 1] ^ K[i + 2] ^ K[i + 3] ^ _SM4_CK[i]) for i in range(32))
        self.e_rk, self.d_rk = K[4:], array('L', reversed(K[4:]))

    def ecb_enc(self, data):
        return array2byte(_ecb_base(self.e_rk, byte2array(data)))

    def ecb_dec(self, data):
        return array2byte(_ecb_base(self.d_rk, byte2array(data)))

    def cbc_enc(self, iv, data):
        return array2byte(_cbc_enc(self.e_rk, byte2array(iv), byte2array(data)))

    def cbc_dec(self, iv, data):
        return array2byte(_cbc_dec(self.d_rk, byte2array(iv), byte2array(data)))
